The important part for answering this question is: A few rubies have been found in the U.S. states of Montana, North Carolina, South Carolina and Wyoming.
This justifies what answer for what question? Q & A: 
Passage: Historically, rubies have also been mined in Thailand, in the Pailin and Samlout District of Cambodia, as well as in Afghanistan, Australia, Brazil, Colombia, India, Namibia, Japan, and Scotland; after the Second World War ruby deposits were found in Madagascar, Nepal, Pakistan, Tajikistan, Tanzania, and Vietnam. In Sri Lanka, lighter shades of rubies (often "pink sapphires") are more commonly found. Republic of Macedonia is the only country in mainland Europe to have naturally occurring rubies. They can mainly be found around the city of Prilep. Macedonian ruby has a unique raspberry color. The ruby is also included on the Macedonian Coat of Arms. A few rubies have been found in the U.S. states of Montana, North Carolina, South Carolina and Wyoming.

Question: Based on this passage, where can rubies be found in the us?
the U.S. states of Montana , North Carolina , South Carolina and Wyoming